// (c) 2006 Richard Grimes
// www.grimes.demon.co.uk

using System;
using System.IO;
using System.Xml;
using System.Security.Cryptography;
using System.Security.Cryptography.Xml;
using System.Security.Cryptography.X509Certificates;

class App
{
   // command line to encrypt: e infile outfile certfile
   //                 decrypt: d infile outfile
   static void Main(string[] args)
   {
      if (args.Length < 2)
      {
         Console.WriteLine("Usage: to encrypt: encrypt e infile outfile certfile");
         Console.WriteLine("       to decrypt: encrypt d infile outfile");
         return;
      }

      bool bEncrypt = (args[0][0] == 'e');
      string inFile = args[1];
      if (!File.Exists(inFile))
      {
         Console.WriteLine("{0} does not exist", inFile);
         return;
      }

      string outFile = null;
      outFile = args[2];
      if (File.Exists(outFile)) File.Delete(outFile);

      string certName = null;

      if (bEncrypt)
      {
         if (args.Length < 4) return;
         certName = args[3];
      }

      if (bEncrypt)
      {
         EncryptDocument(inFile, outFile, certName);
      }
      else
      {
         DecryptDocument(inFile, outFile);
      }
   }

   static void EncryptDocument(string inFile, string outFile, string certName)
   {
      X509Certificate2 cert = GetCertificate(StoreName.AddressBook, certName);
      XmlDocument doc = new XmlDocument();
      doc.Load(inFile);
      XmlElement elem = (XmlElement)doc.GetElementsByTagName("CreditCard")[0];
      EncryptedXml encXml = new EncryptedXml();
      EncryptedData enc = encXml.Encrypt(elem, cert);
      EncryptedXml.ReplaceElement(elem, enc, false);
      doc.Save(outFile);
   }

   static void DecryptDocument(string inFile, string outFile)
   {
   }

   static X509Certificate2 GetCertificate(StoreName storeName, string certname)
   {
      X509Store store = new X509Store(storeName, StoreLocation.CurrentUser);
      store.Open(OpenFlags.ReadOnly);

      X509Certificate2Collection certs =
         store.Certificates.Find(X509FindType.FindBySubjectName, certname, false);
      store.Close();
      if (certs.Count == 0)
      {
         return null;
      }

      return certs[0];
   }
}